I am getting error in alternative step(in COM PORT) while using AT command in Murata ABZ-093 module

I wrote AT and pressed enter and repeated it multiple time.

Below is what i got in response:

02:22:01.835 -> +OK

02:22:01.835 -> 

02:22:04.562 -> +ERR=-1

02:22:04.562 -> 

02:22:06.430 -> +OK

02:22:06.430 -> 

02:22:29.110 -> +ERR=-1

02:22:29.110 -> 

02:22:31.085 -> +OK

02:22:31.132 -> 

02:22:32.895 -> +ERR=-1

02:22:32.895 -> 

02:22:35.200 -> +OK

02:22:35.200 -> 

02:22:37.005 -> +ERR=-1

02:22:37.005 -> 

02:22:38.841 -> +OK

02:22:38.841 -> 

Why i am getting this alternate pattern of OK? What is ERR=-1 and ERR=-3 ??